Processing aids and masterbatches for the same

ABSTRACT

The present invention relates to a processing aid of a non-fluorinated melt-processable polymer and a masterbatch for a processing aid, features the inclusion of a processing aid comprising a fluoropolymer forming clustered secondary particles each having a particle size of 2 μm to 2 mm and being a combination of primary fluoropolymer particles each having a diameter of 0.02 μm to 0.5 μm, and may accelerate the elimination of melt fracture despite the omission of an interfacial agent and decrease extrusion load upon process to thereby enhance productability.

TECHNICAL FIELD

The present invention relates to processing aids and masterbatches for processing aids that are used upon extrusion of a non-fluorinated melt-processable polymer, and more specifically, to processing aids and masterbatches for processing aids that, even without including an interfacial agent, may shorten the melt fracture elimination time while slowing down die buildup and that, when processed, exhibit a decreased extrusion load to thereby enhance productability.

DISCUSSION OF RELATED ART

A quick extrusion process is required to achieve higher productability and cost savings in processing non-fluorinated melt-processable thermoplastic polymers. However, a non-fluorinated melt-processable polymer composition inevitably has a critical shear rate, the excess of which is a cause of a surface roughening, rendering it difficult to obtain a good formed product.

To address such issue while achieving an increased extrusion speed, it has been known to use a fluoropolymer as processing aid.

Korean Patent No. 1996-0000511 (published on Jan. 8, 1996) discloses a fluoropolymer processing aid for melt-processable polymers.

The fluoropolymer processing aid may enhance processability but consumes more melt fracture elimination time.

To accelerate the elimination of melt fracture, it is known to be preferable that the fluoropolymer processing aid is evenly dispersed in the non-fluorinated melt-processable polymer. Korean Patent No. 10-0870388 (published on Nov. 25, 2008) discloses a fluoropolymer processing aid that enhances dispersion of a fluoropolymer processing aid in a non-fluorinated melt-processable polymer.

The fluoropolymer processing aid includes an interfacial agent to reduce the melt fracture elimination time. It, however, may build up a die deposit that is attributed to a carbide created due to the low pyrolysis temperature of the interfacial agent.

PRIOR DOCUMENTS Patent Documents

(Patent Document 1) KR 1996-0000511 B1 published on Jan. 8, 1996.

(Patent Document 2) KR 10-0870388 B1 published on Nov. 25, 2008.

SUMMARY

In using a fluoropolymer as a processing aid for non-fluorinated melt-processable polymers, the prior art has focused on enhancing the degree of dispersing a fluoropolymer processing aid in the non-fluorinated melt-processable polymer using an interfacial agent. The use of interfacial agent may speed up melt fracture elimination but may cause die buildup.

An object of the present invention is to provide a processing aid for non-fluorinated melt-processable polymers and a masterbatch for the processing aid that, even without including an interfacial agent, may shorten melt fracture elimination time, suppress die buildup, and decrease extrusion load when processed to thereby enhance productability.

According to the present invention, it was found that when the fluoropolymer as a processing aid is in a clustered particle form of small particles rather than in a single particle form, the melt fracture elimination time may be reduced and no die buildup may be created even without using an interfacial agent.

To achieve the object, the following means is provided according to the present invention.

The present invention provides a processing aid comprising a fluoropolymer forming clustered secondary particles each having a particle size of 2 μm to 2 mm and being a combination of primary fluoropolymer particles each having a diameter of 0.02 μm to 0.5 μm and formed of a co-polymer of vinylidene fluoride and hexafluoropropylene.

The processing aid further comprises a partitioning agent of one to 20 parts by weight relative to the fluoropolymer of 100 parts by weight and lacks an interfacial agent.

The partitioning agent includes one or more of an inorganic powder with a mean particle size of 0.5 μm to 10 μm or an organic powder with a mean particle size of 1 mm or less. The inorganic powder is one or more species selected from the group consisting of talc, silica, and calcium carbonate, and the organic powder is one or more species selected from the group consisting of an antioxidant, an ultraviolet (UV) absorbent, a flame retardant, a heat stabilizer, a photostabilizer, a metal passivant, an enhancer, a plasticizer, a lubricant, an emulsifier, a pigment, an optical brightener, an antistatic agent, and a foaming agent.

The present invention also provides a masterbatch for a processing aid including a non-fluorinated melt-processable polymer and a processing aid according to the present invention.

The masterbatch for a processing aid may include a processing aid of 0.5 weight % to 20 weight % and a non-fluorinated melt-processable polymer of 80 weight % to 99.5 weight %.

According to the present invention, the processing aid may shorten melt fracture elimination time, delay the creation of die buildup, and decrease extrusion load to thereby enhance productability upon extrusion of the non-fluorinated melt-processable polymer even without use of an interfacial agent. The fluoropolymer processing aid according to the present invention is useful particularly for the extrusion of melt-processable polyolefin.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a photomicrograph of secondary particles of a fluoropolymer prepared according to a first embodiment of the present invention.

FIG. 2 is a photomicrograph of secondary particles of a fluoropolymer prepared according to a second embodiment of the present invention.

FIG. 3 is a photomicrograph of 3M DynamarTM FX-9613.

FIG. 4 is a photomicrograph of Daikin DA-810X.

FIG. 5 is a picture illustrating melt fracture elimination times according to the first embodiment, first comparative example, and fifth comparative example.

FIG. 6 is a picture illustrating die buildup creation times according to a fourth embodiment and fifth comparative example.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, the present invention is described below in detail.

It has been known that, when a shearing force is applied to the non-fluorinated melt-processable polymer in an extruder while in melt during an extrusion process, the fluorine-based processing aid comes in contact with the die surface to create a lubricant layer, which rids the non-fluorinated polymer of melt fracture.

An interfacial agent included in the processing aid to enhance the processability of non-fluorinated melt-processable polymer may accelerate the elimination of melt fracture elimination, but due to its low pyrolysis temperature, may lead to creation of a carbide and an increase in die-deposit that is a cause of die buildup.

Further, exclusion of the interfacial agent from the processing aid composition may slow down the creation of die buildup but may increase the melt fracture elimination time.

The present invention features the provision of a processing aid that, even without an interfacial agent, may shorten melt fracture elimination time, suppress creation of die buildup, and decrease extrusion load upon process.

According to the present invention, a processing aid includes a fluoropolymer having clustered secondary particles each having a particle size of 2 μm to 2 mm, as formed by the combination of primary fluoropolymer particles each having a diameter of 0.02 μm to 0.5 μm.

The fluoropolymer included in the conventional processing aid is constituted of single particles each having a diameter of 2 mm or less, and upon extrusion, it takes a long time for the fluoropolymer to dissolve and contact the die surface to form a lubricant layer.

By contrast, the processing aid according to the present invention forms clustered secondary particles each of which has a particle size of 2 μm to 2 mm and is a combination of primary fluoropolymer particles each having a diameter of 0.02 μm to 0.5 μm and provides the advantage that a lubricant layer may be formed as the primary particles constituting the clustered secondary particles are readily separated upon extrusion and come in quick contact with the die surface.

Fluorinated monomers that may be co-polymerized to form a proper fluoropolymer include vinylidene fluoride, hexafluoropropylene, chlorotrifluoroethylene, and perfluoroalkyl perfluorovinyl ether Specific examples of fluoropolymers available include, but are not limited to, vinylidene fluoride, hexafluoropropylene, chlorotrifluoroethylene, 1-hydro-pentafluoropropylene and 2-hydro-pentafluoropropylene or a co-polymer of 1- or 2-hydro-pentafluoropropylene.

According to the present invention, the processing aid may further include a partitioning agent. The partitioning agent may be added to prevent the fluoropolymer particles from adhering together. The partitioning agent is also called an anti-blocking agent. One to 20 parts by weight of the partitioning agent may be added relative to 100 parts by weight of the fluoropolymer. The partitioning agent may include, but is not limited to, one or more species selected from the group consisting of talc, silica, and calcium carbonate. It is preferable that the partitioning agent is a powder that has a mean particle size of 0.5 μm or more to 10 μm or less.

According to the present invention, the processing aid may further include, in addition to the partitioning agent, additives, such as an antioxidant, an ultraviolet (UV) absorbent, a flame retardant, a heat stabilizer, a photostabilizer, a metal passivant, an enhancer, a plasticizer, a lubricant, an emulsifier, a pigment, an optical brightener, an antistatic agent, and a foaming agent.

According to the present invention, an organic powder that has a mean particle size of 1 mm or less, as well as an inorganic powder such as talk, silica, or calcium carbonate, may be used as the partitioning agent. The organic powder as used may include one or more species selected from the group consisting of an antioxidant, an ultraviolet (UV) absorbent, a flame retardant, a heat stabilizer, a photostabilizer, a metal passivant, an enhancer, a plasticizer, a lubricant, an emulsifier, a pigment, an optical brightener, an antistatic agent, and a foaming agent as added as the additive.

The present invention also provides a masterbatch.

According to the present invention, the masterbatch includes a processing aid according to the present invention and a non-fluorinated melt-processable polymer. In particular, the masterbatch for processing aids according to the present invention may be put to proper use as a processing aid when forming an olefin-based polymer resin.

In the masterbatch for processing aids according to the present invention, the processing aid is evenly dispersed in an olefin-based polymer. The masterbatch may be added when extrusion-forming an olefin-based polymer resin, enhancing forming processability against a lowering in extrusion torque or extrusion pressure.

It is preferable that the olefin-based polymer is a homopolymer of olefin-based monomers or a co-polymer of olefin-based monomers and alpha olefin co-monomers.

The olefin-based monomer includes, but is not limited to, ethylene, propylene, butene, pentene, hexene, octene, decene, dodecene, tetradecene, hexadecene, octadecene, or eicosene.

The co-monomer used for the co-polymerization may be alpha olefin with a carbon number of 4 or more. The olefin whose carbon number is 4 or more includes, but is not limited to, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, or 1-eicosene. Among them, an olefin with a carbon number of 4 to 10 is preferable, and one or several species of alpha olefins together may be used as the co-monomer.

The olefin-based polymer is preferably polyethylene.

According to the present invention, the masterbatch for processing aids is not limited in form to a powder, granules, or pellets, but it is preferably in the form of pellets obtained by melt-mixing.

According to the present invention, the masterbatch for processing aids preferably includes a processing aid of 0.5 weight % to 20 weight % and a non-fluorinated melt-processable polymer of 80 weight % to 99.5 weight %.

According to the present invention, the masterbatch for processing aids may be obtained by blending the processing aid and the non-fluorinated melt-processable polymer with other components as necessary. The other components may include the above-described additives without particularly limited.

According to the present invention, the masterbatch for processing aids may be obtained by mixing the processing aid and the non-fluorinated melt-processable polymer at 120° C. to 200° C.

The configuration and effects of the present invention are now described in further detail in connection with embodiments thereof. The embodiments are provided merely for illustration of the present invention and the scope of the present invention is not limited thereto.

First Embodiment

A processing aid was prepared by dry-blending a partitioning agent of 10 weight % and a fluoropolymer of 90 weight % forming clustered secondary particles each having a particle size of 1 mm or less and being a combination of primary fluoropolymer particles each with a diameter of 0.02 μm to 0.5 μm and constituted of a co-polymer of vinylidene fluoride and hexafluoropropylene. As the partitioning agent, talc (KOCH KC5000) was used. A photomicrograph of the secondary particles of the fluoropolymer is shown in FIG. 1.

Second Embodiment

A processing aid was prepared by dry-blending a partitioning agent of 10 weight % and a fluoropolymer of 90 weight % forming clustered secondary particles each having a particle size of 2 mm or less and being a combination of primary fluoropolymer particles each with a diameter of 0.02 μm to 0.5 μm and constituted of a co-polymer of vinylidene fluoride and hexafluoropropylene. As the partitioning agent, talc (KOCH KC5000) was used. A photomicrograph of the secondary particles of the fluoropolymer is shown in FIG. 2.

Third Embodiment

A processing aid was prepared by dry-blending a partitioning agent of 3 weight % and a fluoropolymer of 97 weight % forming clustered secondary particles each having a particle size of 1 mm or less and being a combination of primary fluoropolymer particles each with a diameter of 0.02 μm to 0.5 μm and constituted of a co-polymer of vinylidene fluoride and hexafluoropropylene. As the partitioning agent, talc (KOCH KC5000) was used.

Fourth Embodiment

A processing aid was prepared by dry-blending a partitioning agent of 3 weight % and a fluoropolymer of 97 weight % forming clustered secondary particles each having a particle size of 2 mm or less and being a combination of primary fluoropolymer particles each with a diameter of 0.02 μm to 0.5 μm and constituted of a co-polymer of vinylidene fluoride and hexafluoropropylene. As the partitioning agent, talc (KOCH KC5000) was used.

Comparison Example 1

DynamarTM FX-9613 (a fluoropolymer of 90 weight % and a partitioning agent of 10 weight %), a processing aid of the 3M company, was prepared. A photomicrograph of 3M DynamarTX FX-9613 is shown in FIG. 3. 3M DynamarTM FX-9613 shows single particles each having a particle size of 1 mm or less.

Comparison Example 2

A processing aid available from Daikin, DA-810X (a fluoropolymer of 97 weight % and a partitioning agent of 3 weight %), was prepared. A photomicrograph of Daikin DA-810X is shown in FIG. 4. Daikin DA-810X shows single particles each having a particle size of 2 mm or less.

Comparison Example 3

A processing aid available from Shine Polymer Technology, 3511N, was prepared. Shine Polymer Technology 3511N includes a fluoropolymer of 50 weight % and an interfacial agent of 50 weight %. Shine Polymer Technology 3511N shows single particles each having a particle size of 2 mm or less.

Experimental Example 1

The processing aids according to the first to fourth embodiments and comparative examples 1 to 3 were dry-blended with a metallocene linear low-density polyethylene (mLLDPE XP9000 available from Daelim Industrial Co., Ltd.: melt index=0.6 g/10 min; and density=0.935 g/cm³) in the amount as shown in Table 1 and was then melt-mixed at 60 rpm and at 170° C., 200° C., and 200° C. using Brabender Instrument's Plasti-Coder (length/diameter-32/1), and the extruded strand was cooled into pallets in a water container.

While each pallet was extruded by Brabender Instrument's single-screw extruder, Plastograph EC Plus (length/diameter=32/1) equipped with a 80 mm-long and 1.5 mm-diameter die at the screw rotation count of 150 rpm, die temperature of 230° C., and cylinder temperature of 170° C., 230° C., and 230° C., the melt fracture elimination time and die buildup creation time were observed, and the die pressure was recorded as shown in Table 1.

For the melt fracture elimination time, the time from when the pellet was put in the hopper—this moment was taken as 0—to when the melt fracture was cleared out to smooth down the overall surface of the formed product was measured by naked eyes and palpation.

A picture illustrating the respective melt fracture elimination times for first embodiment, comparative example 1, and comparative example 5 is shown in FIG. 5. A picture illustrating the respective die buildup formation times for the fourth embodiment and comparative example 5 is shown in FIG. 6.

TABLE 1 Processing aid Melt composition Pro- fracture (weight %) cessing elimi- Die Die Inter- aid nation buildup pres- Fluoro- facial amount time creation sure polymer Talc agent (ppm) (min.) time (bar) Embodiment 90 10 — 400 10 60 min. 80 1 Embodiment 90 10 — 400 10 60 min. 85 2 Embodiment 97 3 — 350 15 60 min. 80 3 Embodiment 97 3 — 350 20 60 min. 90 4 Comparison 90 10 — 400 50 60 min. 95 Example 1 Comparison 97 3 — 350 40 50 min. 105 Example 2 or less Comparison 50 — 50 800 30 30 min. 90 Example 3 or less

As evident from Table 1 and FIG. 5, the processing aids according to the first through fourth embodiments show remarkably reduced melt fracture elimination times and lower die pressures as compared with those of the processing aids according to comparative examples 1 and 2.

Further, the processing aids according to the first through fourth embodiments may be verified to show shortened melt fracture elimination times as compared with that of the processing aid according to comparative example 3 containing an interfacial agent.

As evident from Table 1 and 6, the processing aids according to the first through fourth embodiments cause no die buildup for 60 minutes whereas the processing aid according to comparative example 3 forms die buildup within 30 minutes due to the interfacial agent included.

Accordingly, the processing aid according to the present invention may shorten melt fracture elimination time and decrease extrusion load to thereby enhance productability upon extrusion despite the exclusion of an interfacial agent.

Comparison between the photomicrographs of FIGS. 1 and 2 according to the present invention and the photomicrographs of FIGS. 3 and 4 for those being commercially available is made as follows.

From the photomicrographs of FIGS. 1 and 2, it can be shown that the fluoropolymer particles according to the present invention are clustered secondary particles each having smaller primary particles put together. The processing aid according to the present invention is prepared by dry-blending the clustered secondary particles and a partitioning agent. Dry-blending is a blending process that does not involve external actions, such as heat or pressure, which may deform the clustered secondary particles. Accordingly, the processing aid according to the present invention remains in the form as shown in FIGS. 1 and 2.

From the photomicrographs of FIGS. 3 and 4, on the other hand, the processing aids being commercially available may be verified to be in the form of single particles. 

What is claimed is:
 1. A processing aid comprising a fluoropolymer forming clustered secondary particles each having a particle size of 2 μm to 2 mm and being a combination of primary fluoropolymer particles each having a diameter of 0.02 μm to 0.5 μm and formed of a co-polymer of vinylidene fluoride and hexafluoropropylene.
 2. The processing aid of claim 1, further comprising a partitioning agent of one to 20 parts by weight relative to the fluoropolymer of 100 parts by weight.
 3. The processing aid of claim 2, wherein the partitioning agent includes one or more of an inorganic powder with a mean particle size of 0.5 μm to 10 μm or an organic powder with a mean particle size of 1 mm or less, wherein the inorganic powder is one or more species selected from the group consisting of talc, silica, and calcium carbonate, and the organic powder is one or more species selected from the group consisting of an antioxidant, an ultraviolet (UV) absorbent, a flame retardant, a heat stabilizer, a photostabilizer, a metal passivant, an enhancer, a plasticizer, a lubricant, an emulsifier, a pigment, an optical brightener, an antistatic agent, and a foaming agent.
 4. A masterbatch for a processing aid, the masterbatch comprising a non-fluorinated melt-processable polymer and the processing aid of claim
 1. 5. The masterbatch of claim 4, the masterbatch comprising the non-fluorinated melt-processable polymer of 80 weight % to 99.5 weight % and the processing aid of 0.5 weight % to 20 weight %. 